Martin JRM Mars

{| |} The Martin JRM Mars is a large, four-engined cargo transport seaplane originally designed and built in limited numbers for the U.S. Navy during the World War II era. The surviving aircraft were later converted for civilian use, after the war and their Navy service, as firefighting water bombers.

The Mars was the largest Allied flying boat to enter production, although only seven were built. The United States Navy contracted the development of the XPB2M-1 Mars in 1938 as a long range ocean patrol flying boat, which later entered production as the JRM Mars long range transport.

Design and development

The Glenn L. Martin Company effectively scaled up their successful PBM Mariner patrol bomber design to produce the prototype XPB2M-1 Mars. After flight tests with the XPB2M between 1941 and 1943, she was passed on to the Navy. The original patrol bomber concept was considered obsolete by this time, and the Mars was converted into a transport aircraft designated the XPB2M-1R. The Navy was satisfied with the performance, and ordered 20 of the modified JRM-1 Mars. Though the original Hawaii Mars was lost in an accident on Chesapeake Bay, the other 5 Mars were completed, and the last delivered in 1947.

Operational history

U.S. Navy service

Named the Marianas Mars, Philippine Mars, Marshall Mars, Caroline Mars, and a second Hawaii Mars, the 5 production Mars aircraft entered service ferrying cargo to Hawaii and the Pacific Islands. The last production airplane (the Caroline Mars) was designated JRM-2, powered by Pratt & Whitney R-4360 engines, and featured a higher maximum weight and other improvements. On 5 April 1950, the Marshall Mars was lost near Hawaii when an engine fire consumed the airplane after her crew had evacuated. The remaining "Big Four" flew record amounts of Naval cargo on the San Francisco-Honolulu route efficiently until 1956, when they were parked at NAS Alameda. The Maryland Aviation Museum and British Columbia Aviation Council have initiated a joint effort to preserve the aircraft, one in Maryland and the other at their current location in Canada. On 13 April 2007, TimberWest announced the sale of both aircraft to Coulson Forest Products, a local forestry company in Port Alberni, British Columbia. The two surviving tankers are based at Sproat Lake near Port Alberni. On 25 October 2007, the Hawaii Mars ("Redtail") arrived at Lake Elsinore in Southern California, on a private contract, to assist with the firefighting efforts containing the California wildfires of October 2007. The Philippine Mars is undergoing "extensive maintenance and renovation" and will not be ready to fly again until 2010. , the Hawaii Mars was in service fighting the La Brea fire east of Santa Maria in Southern California.

Based on historical data, each plane can make a drop every fifteen minutes. Working in tandem, this equates to 7,200 US gallons (27,276 litres) every seven minutes and each drop can cover an area of up to 4 acres (1.6 hectares). The aircraft can also carry up to 600 US gallons (2,270 litres) of foam concentrate for gelling the load drop. They are used to fight fires along the coast of British Columbia and sometimes in the interior. As of July 29, 2010, the Martin Mars was being used to fight the Mason Lake/Bonaparte Lake fire north of Kamloops.

Variants

;XPB2M-1 :Model 170 prototype long-range patrol flying boat powered by four Wright R-3350-8's piston engines, one built, converted to XPB2M-1R. ;XPB2M-1R :Prototype converted in December 1943 as a prototype transport version, armament removed, installation of additional cargo hatches and cargo loading equipment, existing hatches were enlarged and the decking was reinforced. ;JRM-1 :Model 170A, production long range transport variant, originally 20 aircraft ordered later reduced to 6. Single-tail design, and having a longer hull with fewer bulkheads and a larger maximum take-off weight. It had also been fitted with equipment for overhead cargo handling and was powered by four Wright R-3350-24WA Cyclone engines with 4-bladed propellers, five built, surviving four converted to JRM-3. ;JRM-2 :The last JRM-1 on order was completed as the JRM-2 with the engines changed to 3,000hp Pratt & Whitney R4360-4T engines with 4-blade, 16ft 8in diameter Curtiss Electric propellers. Gross weight increased by 20,000 lbs. ;JRM-3 :Model 170B, conversion of the remaining four JRM-1s re-engined with 2,400hp Wright R3350-24WA engines turning 16ft 8in Curtiss-Electric props, of which the inboard two engines were fitted with reversible-pitch devices.

Aircraft

The Old Lady - serial Bu 1520. Ordered on 23 August 1938 and completed as the prototype long-range patrol XPB2M-1, it was first flown on 3 July 1942 and converted in December 1943 to transport variant and designated XPB2M-1R. Assigned initially to VR-8 (NAS Patuxent River) for crew training, it was later transferred to VR-2 (NAS Alameda) and scrapped in 1945.

Hawaii Mars I - JRM-1 Bu. 76819 first flown on 21 July 1945 and delivered to the United States Navy. It sank on 5 August 1945 in Chesapeake Bay and was disposed as scrap.

Philippine Mars - JRM-1 Bu. 76820, delivered to the USN on 26 June 1946 and assigned to VR-2 (NAS Alameda). Converted and re-designated JRM-3. Withdawn from service on 22 August 1956 and sold in 1959, it was converted to forest fire fighting aircraft and registered CF-LYK (later C-FLYK). The aircraft is still flying with Coulson Group at Sproat Lake, British Columbia, Canada.

Marianas Mars - JRM-1 Bu. 76821, delivered to the USN on 26 February 1946 and assigned to VR-2 (NAS Alameda). Converted and re-designated JRM-3, it was withdrawn from service on 22 August 1956 and sold in 1959. Converted to forest fire fighting aircraft and registered CF-LYJ, the aircraft crashed into Mount Moriarty near Nanaimo, Vancouver Island, on 23 June 1961, when the water drop mechanism failed, leaving the aircraft unable to climb quickly enough to clear a mountain. In the ensuing crash, the crew of four were killed.

Marshall Mars - JRM-1 Bu. 76822, delivered to the USN, converted and re-designated JRM-3. It was destroyed by an engine fire and sank on 5 April 1950 off Diamond Head, Oahu.

Hawaii Mars II - JRM-1 Bu. 76823, delivered to the USN on 23 April 1946 and assigned to VR-2 (NAS Alameda). Converted and redesignated JRM-3, it was withdrawn from service on 22 August 1956 and sold in 1959. Converted to forest fire fighting aircraft and registered CF-LYL (later C-FLYL), it is still flying with Coulson Group at Sproat Lake, British Columbia, Canada.

Caroline Mars - * JRM-2 Bu. 76824, delivered to the USN on 10 May 1948 and assigned to VR-2 (NAS Alameda). It was sold in 1959 and converted to forest fire fighting aircraft by Forest Industry Flying Tankers. Registered CF-LYM. the aircraft was destroyed during Typhoon Freda at Victoria, Canada on 12 October 1962. |crew=four (with accommodations for a second relief crew) |capacity=133 troops, or 84 litter patients and 25 attendants |payload main=32,000 lb |payload alt=15,000 kg |payload more=of cargo, including up to seven jeeps |length main=117 ft 3 in |length alt=35.74 m |span main=200 ft 0 in |span alt=60.96 m |height main=38 ft 5 in |height alt=11.71 m |area main=3,686 ft² |area alt=342.4 m² |empty weight main= 75,573 lb |empty weight alt=34,279 kg |loaded weight main= 90,000 lb |loaded weight alt= 40,820 kg |max takeoff weight main=165,000 lb |max takeoff weight alt=74,800 kg |engine (prop)=Wright R-3350-24WA Duplex Cyclone |type of prop=18-cylinder radial engines |power main=2,500 hp |power alt=1,900 kW |number of props=4 |max speed main=192 knots |max speed alt=221 mph, 356 km/h |cruise speed main=165 knots |cruise speed alt=190 mph, 305 km/h |range main= 4,300 nautical miles |range alt=5,000 mi, 8,000 km |ceiling main=14,600 ft |ceiling alt=4,450 m |climb rate main= |climb rate alt= |loading main= |loading alt= |power/mass main= |power/mass alt= }}

See also

References

;Notes

;Bibliography

Bridgeman, Leonard. “The Martin Model 170 Mars.” Jane's Fighting Aircraft of World War II. London: Studio, 1946. ISBN 1-85170-493-0.

Coulson, Wayne and Steve Ginter. The Mighty Martin Mars: From 1945 US Navy Transport to 21st century initial attack firefighting. Port Alberni, BC, Canada: Half Moon Bay Publications, 2009. ISBN 978-0-9812987-0-2

Ginter, Steve. Martin Mars XPB2M-1R & JRM Flying Boats (Naval Fighters 29). Simi Valley, California, USA: Ginter Books, 1995. ISBN 0-94261-229-9.

External links

"The Mars Makes Good", April 1944 article

Popular Mechanics, June 1944">"Life Line Of The Fleet," pp. 69,70 photos, Popular Mechanics, June 1944

Flying Tankers, Inc.

Martin Mars Page of the Glenn L. Martin Maryland Aviation Museum

Museum-Canadian Mars Alliance Created

Lake Elsinore">NBC News video of Hawaii Mars arriving at Lake Elsinore

Category:United States military transport aircraft 1940-1949 Category:Seaplanes and flying boats Category:Martin aircraft Category:Firefighting equipment Category:Aerial firefighting